1. Field of the Invention
The present invention relates to an acoustic wave contact detecting apparatus, such as an ultrasonic touch panel.
2. Description of the Related Art
Ultrasonic acoustic wave contact detecting apparatuses are in widespread use. Examples of their applications include operating screens of personal computers, ticket dispensers at train stations, copiers installed in convenience stores, and ATM's at financial institutions. These acoustic wave contact detecting apparatuses utilize transducers, including piezoelectric vibrators (piezoelectric elements) provided on a substrate (touch panel) formed of glass or the like. These transducers function both as generating means for bulk waves and as sensors for detecting acoustic waves which are scattered by a finger or the like that contacts the touch panel. The transducers and controllers of control circuits are connected by wires which are insulated by insulative coverings.
However, in the case that the periphery of the substrate is covered by bezels and the like, it is difficult to arrange the wires due to the scarcity of space.
There are also cases in which flat cables, such as Flexible Printed Circuits (FPC), are employed, as disclosed in Japanese Unexamined Patent Publication No. 6 (1994)-324792 (page 5, FIG. 9). FPC's are flexible boards on which circuits are printed.
In the case that FPC's are employed for connection with a substrate, external electromagnetic waves easily enter the signal circuits (signal wires) formed on the FPC. In addition, there is a problem that electromagnetic waves radiate to the exterior from the signal wires. The reason for this is because the signal wires of the FPC's are structured such that they are substantially exposed to the exterior. In the case of the FPC's employed in Japanese Unexamined Patent Publication No. 6-324792, shield electrodes, which are larger than the FPC's, cover the FPC's to function as shield members. However, this construction adds to the cost of the apparatus, due to the necessity of separate members.